Field of the Invention
The present invention relates to an imprint apparatus and an article manufacturing method.
Description of the Related Art
Optical imprinting is a method for forming a pattern on a substrate. In the optical imprinting, a mold (also referred to as a “mask”) on the surface of which a relief is formed is brought into contact with a light-curable resin (imprinting material) applied on a substrate, and light, such as ultraviolet light, is radiated thereon to cure the light-curable resin. Then, by removing the mold from the light-curable resin, a pattern in which high portions and low portions are the reverse of those of the pattern on the mold is formed on the substrate.
Various imprint apparatuses, which vary in the method of curing resin and in purpose, have been proposed. For mass-production apparatuses, such as apparatuses for producing semiconductor devices, the use of step-and-flash imprint lithography (hereinbelow, SFIL) is effective.
Such an imprint apparatus employs a die-by-die alignment method to align the pattern on the mold with a shot area of the substrate. In this method, for each shot area of the substrate, a mold-side mark provided on the mold and a substrate-side mark provided on the substrate are optically detected, and a positional deviation and a shape difference between the pattern on the mold and the shot area of the substrate are corrected.
To maintain the alignment accuracy, the mark waveform obtained by the optical detection needs to approximate the shape of the mark, etc. Japanese Patent Laid-Open No. 2006-294854 discloses an alignment method in which a mark (waveform) the score (indicating the mark waveform likelihood) of which is abnormal is distinguished from a mark (waveform) the score of which is normal, so that only the mark with the normal score is used for alignment.
In an imprint apparatus, sometimes, alignment between the pattern on the mold and the shot area of the substrate is not performed properly, decreasing the alignment accuracy. A cause of this is, for example, an alignment-mark detection fault caused by a foreign particle trapped between a mold-side mark and a substrate-side mark (mark pair).
If the method disclosed in Japanese Patent Laid-Open No. 2006-294854 is applied to such an imprint apparatus, even though the score indicating the mark waveform likelihood is normal, a measurement error (a mark detection fault), i.e., inability to properly measure the position of the alignment marks, may occur, decreasing the alignment accuracy.